Re: model 7 receiver
If you were to order a new, never assembled action direct from Remington you could build a pistol out of it. To use a Savage action it must be the same thing, a new, undesignated action. When it's transferred to you on the federal transfer form it will be sold as an action, not a rifle or pistol. It's the same thing that's done to build AR style pistols.
There are some tricks to building a SP which will technically still meet the legal requirements of a rifle, allowing you to use a rifle action for the build. That's up to you to figure out though.
As far as a stock, any custom stock maker will be able to inlet for any action you want.